Drive mechanism

Abstract

The invention relates to a drive mechanism for all-wheel drive vehicles, comprising a variable-speed transmission and an interaxle differential for distributing drive torque onto a first and a second axle differential via which the front wheels and rear wheels of the motor vehicle are driven. A drive shaft of the variable-speed transmission drives a driving element of the interaxle differential while output elements of the interaxle differential are connected in a driving manner to the axle differentials. Also provided is a clutch which influences the output torque distribution. An infinitely 304 variable output torque distribution has the following characteristics:—the output gear ratios between the first and the second axle differential are different;—the configuration of the interaxle differential ( 16 ) is such that different output torques are provided to the axle differentials, the higher output torque being applied to the axle differential that has the shorter gear ratio;—a slip-controlled multi-disk clutch ( 46 ) is mounted between the driving element ( 32 ) of the interaxle differential and the output element ( 36 ) having the lower output torque; and—the multi-disk clutch ( 46 ) can be controlled according to operating parameters of the motor vehicle in order to variably distribute the output torques of the interaxle differential.

1 . A drive mechanism for all-wheel-drive vehicles comprising: 
 a change-speed gear and an interaxle differential for output torque distribution to a first and a second axle differential by way of which the front wheels and the rear wheels of the vehicle are driven,    a drive shaft of the change-speed gear driving a drive element of the interaxle differential and output elements being drive-connected to the axle differentials and a clutch affecting the output torque distribution being provided,    wherein:    the output transmission ratios between the first and the second axle differential are different;    the interaxle differential is configured such that the output torque to the two axle differentials is different, the higher output torque being applied to the shorter transmission axial differential;    a slip-controlled disk clutch is introduced between the drive element of the interaxle differential and the output element with the lower output torque; and    the disk clutch is controllable as a function of the operation parameters of the vehicle for variable distribution of the output torque values of the interaxle differential.    
   
   
       2 . The mechanism as claimed in  claim 1 , wherein the shorter output transmission is effected at the axle differential driving the rear wheels of the vehicle and wherein the higher output torque of the interaxle differential is switched to this axle differential ( 19 ).  
   
   
       3 . The mechanism as claimed in  claim 1 , wherein the interaxle differential is an epicyclic gear.  
   
   
       4 . The mechanism as claimed in  claim 1 , wherein the drive shaft of the speed change gear connected to the drive element is a hollow shaft on the end of which facing the drive element the disk clutch is mounted which may be coupled by the drive shaft to the output shaft of the interaxle differential.  
   
   
       5 . The mechanism as claimed in  claim 1 , wherein the drive element of the planet wheel is the planet wheel carrier and wherein the output elements are in the form of the sun wheel and the external gear.  
   
   
       6 . The mechanism as claimed in  claim 1 , wherein the external gear of the planet wheel with the higher output torque is drive-connected to the shorter transmission axle differential for driving the rear wheels of the vehicle.  
   
   
       7 . The mechanism as claimed in  claim 1 , wherein the epicyclic gear is a double epicyclic gear the radially inner planet wheels of which mesh with the sun wheel and the radially outer planet wheels of which mesh with the external gear, wherein, in addition, the external gear forms the drive element, and wherein the output element is the sun wheel with respect to the axle differential with shorter transmission.  
   
   
       8 . The mechanism as claimed in  claim 1 , wherein the slip-controlled disk clutch is controlled as a function of operation parameters and/or parameters of the operating dynamics of the vehicle in such a way that the output torque of the interaxle differential may be adjusted continuously from the structurally determined output torque distribution with priority at one axle differential by way of a neutral distribution to an output torque distribution with priority at the other axle differential.  
   
   
       9 . The mechanism as claimed in  claim 1 , wherein the operation parameters are a plurality of electronically recorded driving programs of an automatic speed change gear of the vehicle in the preselection of which different output torque distributions of the interaxle differential are determined by appropriate actuation of the disk clutch.  
   
   
       10 . The mechanism as claimed in  claim 1 , wherein the driving dynamics parameters are stored in a control unit of an electronic driving stability program of the vehicle and wherein, in addition to the conventional engagement operations such as brake engagement and reduction of the drive torque of the driving machine, the output torque distribution of the interaxle differential is changed in the direction of neutral and optionally beyond by means of appropriate additional actuation of the disk clutch.